someone who acts so stupid it makes the person who is with them feel so cripilingly disabled they can barely walk because of the sheer velocity of the action caused by someone being very dumb . when calling someone a ploff it is usualy very reserved and not used willy nilly . its intended to be used at the exact moment of inpact of the person being stupid followed by some retarded noises and a bent walk with a bent left arm and wrist and a screwed up face followed by some more retarded orgasems.

ya complete ploff , you stupid ploff , you fucking ploff , nnnmmmmnnnn u fucking ploff (and make like you cant walk because the stupidity of the person is so mutch it makes you cripled temporaliry).